Railway track circuit apparatus



July 2, 1940.

R. M. GILSON RAILWAY TRACK CIRCUIT APPARATUS Filed Nov. 29, 1939 Vg@ @i 5B i X; ou@ h g55# vo N b m (S I q (f1 \7h A; E5 x f 4@ Tw un KO @Q1 A MS l) NHQ w N INVENTOR OM Rabep 'lsan.

` @l 1% BY 'vmv' HIS ATTORNEY Patented July 2, 1940 UNITED STATES PATENT OFFICE RAILWAY TRACK CIRCUIT APPARATUS application November 29, 1939, serial No. 306305 7 Claims.

My invention relates to railway trackcircui-t apparatus, and particularly to apparatus for track circuits using coded current.

Railway track circuits have been proposed which use time spaced impulses of direct current with the individual impulses of relatively high peak voltage and of short dura-tion as compared with the duration between successive impulses.

The high peak voltage serves as an aid to the l0v shunting sensitivity of the track circuit and the short duration serves to limit the output of the current source to a. relatively low energy level.

In such track circuits code following track relays v are provided for controlling the signaling circuits. It has been found that When adverse trainshunting conditions prevail due to rusty rail surfaces, light-Weight high-speed trains or other operating conditions, a few impulses of current of sufficient magnitude to operate the track relay may reach the relay new and then past a poor train shunt with the result an undesirable proceed signal indication may be established for an interval.-

Accordingly, main object of my invention is the provision of novel and improved apparatus for use with track circuits supplied with coded current wherewith an undesirable proceed signal indication due to adverse train shunting conditiene is avoided. The abo-ve object together with other advantages of my invention I accomplish by the provision of a chain of relays Which are sequentially picked up by consecutive operations of the code following track relay and the last one of which chain of relays must be picked up before a proceed signal is displayed. Consequently a number of successive impulses of the track circuit current predetermined according to the number of rela-ys provided in the chain 'of relays must operate the code following track relay before the proceed signal circuit is closed. The 40 loss of a single one of the successive impulses of the track circuit current drops all ofthe relays already operated thus necessitating a new start in the counting of the current impulses. In other words, the chain of relays governed by the code following track `relay in accordance With my invention causes the display of a stop signal even when the train shunt is effective only intermittently While a train occupies the track circuit, and a false proceed signal due to a lossv of train shunt is avoided unless such loss of train shunt persists for more than the number of current impulses necessary to make a complete count of the chain of relays.

.I shall...describe' one form of apparatus-em# bodying my invention, and shall then point out the novel features thereof in claims.

In the accompanying drawing which is a preferre'd forni of apparatus embodying my invention, the reference characters Id and Ib designate the track rails ofa stretch of railway over which traflic normally moves in the direction indicated by an arrow and which rails are formed by the usual insulated rail joints 2 into a track section W--X which section may be one of a series of consecutive sections of a signal system. The section W-X is" provided with a track circuit comprising a source of coded direct current connected across the 'rails at one end of the section and a code following track relay connected across the rails at the other end of the section.

The source of coded direct current for the track circuit of section W-X includes a battery 5, a code transmitter CT and a track transformer WT. As here shown the secondary Winding l? o'f transformer WT is connected across the rails adjacent the eizit end of section W-'-X over wires I and 8, a current limiting resistor 9 being pref erably interposed in Wire 8. The primary winding Ill of transformer WT is connected with batter-yt overva contact meinberll of the code transmitter CT. ln concerisierl Vl2 is pmferatiy connected 'cross'kpriinay Winding I0 to improve the operation. The 'code transmitter CT may take the form of anyone of ,several Well-known structuresufor such devices and it is sufficient to point out that as long as "the operating Wind# ing I3 of code transmitter CT is supplied tvithA current from a Asource Whose terminals are in; dicate'd atl?,l and G, the contact member il is operated at a preseletd code rate, such as, for example, '75', operations per minute. The Contact member l I is biased to normally engage a contact I4 and is operated to break engagement there# with once each operation of .thefcde' transmitter. Wlien contact I I gId is closed current ovvs from battery 5 to primary winding I0 and magnetic energy is 4stored in theI magnetic circuit of the transformer The circuit including battery 5 and primary Winding I0 is so proportioned as to its timeconstant` that the magneticv energy builds up relatively slow and little if any electromotive force is induced inv secondary Winding- 6. At least the electromot-ive force induced in secondary' Winding I5 When energy builds up in transformer WT is so small in magnitudev it can be neglected; When" contact member II of code transmitter CT breakse'ngag'ement with contact I4, the aowl of current from battery 5 is interrupt'edand the-magnetic energy'stored in transformer WT decays rapidly so that an electromotive force of relatively 4large magnitude is induced in secondary winding 6 and a current impulse of relatively high peak voltage is supplied to the track circuit of section W-X. This impulse of current is of a given polarity and of short duration, at least the duration of the current impulse is short as compared with the duration between successive current impulses when the code rate of 75 impulses per minute is used. It follows that as long as code transmitter CT is operated current impulses of the preselected code rate of 75 impulses perminute are supplied to the track circuit of section VV-X.

It will be understood, of course, that I do not limit my invention to coded current having 75 impulses per minute or to impulses of relatively high peak voltage and shortduration but such code rate and characteristics have been found satisfactory. i' y l,

'Ihe track circuit of section W-X is provided with a code following track relay CF. The code following relay CF may be any one of several well-known types and in the instant case relay CF is a neutral relay whose operating winding |5 is connected across the rails adjacent the entrance end of section W-X over wires |6 and Relay CF is provided with two contact members I8 and I9 which are biased to engage back contacts 26 and 2|, respectively, and are raised to engage respective front contacts 22 and 23 when the relay is energized. Relay CF is effectively energized to operate its contact members I8 and I9 by each individual current impulse supplied to the track circuit by the apparatus at the exit end of section W-X. Consequently, contact members |8 and I9 are operated at the code rate preselected for the track circuit, and in this case are operated at the rate of 75 times per minute when the section W--X is unoccupied, but both contact members I3 and I9 are inactive in engagement with their respective back contacts 20 and 2| when the section is occupied by a train such as indicated at TV in the drawing.

The code following track relay CF has assc, ciated therewith a chain of relays consisting of two control relays FSA and BSA, two repeater relays Xl and X2, and four counting relays CI', C2, C3 and C4.

The control relays FSA and BSA are slow releasing in character, their release periods being suiiicient to bridge from one impulse to the next of the track circuit current but insuicient to bridge two such impulses. XI and X2 and the counting relays CI, C2, C3 and C4 are each of the usual acting type.

The control relays FSA and BSA and the counting relay C4 control the operating circuits of a wayside signal Sl which governs traic through the section W-X. Signal SI may be any of the standard types and as here shown is a color light signal provided with two lamps Gv and R for displaying a proceed and a stop signal indication, respectively.

It is believed that the circuits governed by the code following track relay CF for operating the associated chain of relays can best be understood by a description of their operation through the steps necessary before a proceed signal indication for signal S| is-effected. At the start it will be assumed that section W-X is occupied by the train TV so that the code following track relay CF is inactive and all of the other relays are released as shown in the drawing. With control The repeater relaysV relay FSA released closing back contact 68 a simple circuit easily traced is closed for illuminating the lamp R of signal SI causing that signal to display its stop indication. It is also to be observed that when relay FSA is picked up closing front contact 65 and relay BSA is released closing back contact 69, a second circuit is completed for illuminating lamp R of signal Si. Furthermore when both control relays FSA and BSA are picked up closing front contacts 65 and 66, respectively, and the last relay C4 of the chain of relays is released closing back contact 10, a third circuit is formed for lamp R of signal Sl. Hence, the lamp R of signal SI is illuminated and a stop signal displayed by signal SI until both control relays FSA and BSA, and the last relay.7 C4 of the chain of relays .are picked up. To bring about such operation of the control relays FSA and BSA and the last relay C4 of the chain of relays requires ten operation steps.

Assuming the train TV which occupies section W-X moves out of the section, the first current impulse supplied to the track circuit after the train vacates the section initiates the first operation step. On the rst operation step code following track relay CF is picked up closing front contact |8-22 so that current ows from the terminal B of the current source over front contact |8-22, wire 24, back contacts 25, 26, 21, 28, 29, 30 and 3| of relays C4, C3, C2, CI, X2, XI and BSA, respectively, winding of relay FSA and to terminal C of the current source, and relay FSA is picked up. Since control relay FSA is slow releasing in character it is thereafter energized and held picked up over its stick circuit including front contact |8-22 of relay CF andv its own front contact 72 as long as the track relay CF isA operated by each successive impulse of the track circuit current. If track relay CF is not operated by any one of the impulses of the track circuit current, the control relay FSA is released because its slow release period is not sufln cient to bridge the interval of two impulses of the track circuit current. Furthermore, if control relay FSA isronce released, it cannot be reenergized except over its pick-up circuit which includes the back contacts 25 to 3|, inclusive, of the several associated relays.

I'he second operation step is initiated when the rst impulse of track circuit current ceases and track relay CF is released to close back contact |8--20. Current now flows from terminal B of the current source over back contact |8-20 of relay CF, front contact 32 of relay FSA, wind# ing of relay BSA and to terminal C, and relay BSA is picked up. Since control relay BSA is slow releasing in character it is retained energized as long as track relay CF is operated at the pre-v selected code rate and the control relay FSA is picked up closing front contact 32.

The third operation step is initiated when a second impulse of current is supplied to the track circuit to pick up the track relay CF. Current now iiows from terminal B over front contacts 33 and 34 of relays BSA and- FSA, respectively, frontl contact |9-23 of relay CF, wire 35, back contacts 36,131, 38 and 39 of relays C4, C3, C2 and Ci, respectively, Winding of relay Xl and to terminal C, and relay XI is picked up after which it is held picked up over a stick circuit involving terminal B, front contacts 33 and 34, Wire 51, back contact 40 of relay X2, front contact 4| and Winding of relay XI, and terminal C.

The fourth operation step is started when the second impulse of track circuit current ceases 'Ill causing track relay CF to be released. Current now flows from terminal B over front contacts 33 and 34 of relays BSA and FSA, respectively, back contact l9-2I of relay CF, front contact 42 oi relay Xl, back contact 43 of relay X2, Wire 44, back contacts 45 and 45 of the even numbered relays C4 and C2 of the counting relays, Winding of relay CI and to terminal C, and relay Cl is picked up. Relay CI is then retained energized over a stick circuit including terminal B, front contacts 33 and 34, Wire 51, front contact 41 and winding of relay Cl and terminal C as long as the two control relays FSA and BSA are picked up closing front contacts 34 and 33.

The iiith operation step is eiected when the third impulse of current is supplied tov the track circuit to pick up the track relay CF and current flows from terminal B over front contacts 33 and 34 of relays BSA and FSA, respectively,

' iront Contact |323 of relay CF, Wire 35, back contacts 33, 31 and 38 of relays C4, C3 and C2, respectively, front contact 43 of relay Cl, Wind ing of relay X2 and to terminal C, and relay Xi is picked up opening at its back contact 40 the f stick circuit for repeater relay Xl so that relay Xi is immediately released. Repeaterrelay X2 is then retained energized over a stick circuit involving terminal B, front contacts 33 and 34,

Wire 51, back contact 50 of relay Xl, front contact 5l and Winding of relay X2 and terminal The sixth operation step is elected when the third impulse of track circuit currentA ceases so that relay CF is released and current flows' from terminal B over front contacts 33 and34 of relays ofV relay CF, back contact 52 of relay Xi, front Contact 53 of relay X2, wire 54, back contact 55 of relay C3, front contact 5E of relay Cl, Winding of relay C2 and to terminal C, and relay C2 is picked up. Relay C2 is then retained energized over a stick circuit Which is the same as the stick circuit traced for relay CI up to Wire 51, thence over front contact 58 and Winding of relay C2 to v terminal C.

The seventh operation step is eiected when the fourth impulse of current is supplied to the track circuit causing track relay CF to be picked up and current iiovvs from terminal B over front l contacts 33 and 34 of relays BSA and FSA, respectively, front contact l9--23 of relay CF, Wire 35, back contacts 3B and 31 of relays C4 and C3, respectively, front contact 59 of relay C2, Winding of repeater relay XI and to terminal C, and relay XI is then picked up to open at its backA Contact 50 the stick circuit for relay X2 so that repeater c of relay CF, front contact 42 of relay XI, back contact 43 of relay X2, Wire 44, back contact 45 of relay C4, front contact 3G of relay C2, Winding of relay C3 and to terminal C, and relay C3 is picked up. Relay C3 is then retained energized over a stick circuit which is the same as traced for relay CI up to wire 51 and thence over front contact 5| and Winding of relay C3 to terminal C.

VThe ninth operation step is effected when the fifth impulse of current is supplied to the track circuit causing track relay CF to be picked up so that current flows from terminal B over lfront contacts 33 and 34 of relays BSA and FSA, respectively, front contact lli-'23 of relay CF, Wire 35, back contact `36 of relay C4, front contact 62 of relay C3, winding of repeater relay X2 and to terminal C, and relay X2 is again picked up opening at its' back contact 40 the stick circuit for repeater relay XI with the result that relay XI is immediately released closing back contact 53 and relay X2 is retained energized over its previously traced stick circuit. i

For the tenth operation step the fifth impulse of track circuit current ceases so that track relay CF is released and current flows from terminal B over front contacts 33 and 34 of relays BSA and FSA, respectively, back contact l92| of relay CF, back contact 52 of relay XI, front contact 53 of relay X2, Wire 54, front contact 63 of relay C3, winding of relay C4 and to terminal C, and relay C4 is picked up after which it is retained energized over a stick circuit which is the same'as traced for relay CI up to wire 51 and thence over front contact 34 and Winding of relay C4 to terminal C.

With the last relay C4 of the chain of relays picked up opening back contact 10, the circuit for lamp R of signal Sl is opened and the lamp is dark. A proceed signal circuit can now be traced from terminal B over front contacts 65, 65 and 5 1 of relays FSA, BSA and C4, respectively, lamp G of signal SI and to terminal C, and the lamp G is illuminated so that signal Sl displays a pro'- oeed signal.

It is to be observed that on the next impulse of track circuit current and relay CF is picked up closing front contact I3-23 a circuit is comrelay' Xlso that relay X2 is released closing back contact lll and relay XI is retained energized over its stick circuit. From this point on relay XI is retained energized over its stick circuit so that the repeater relays Xl andX `are not further operated, relay `Xl being picked up and relay X2 being` released.

Assuming train TV occupies section W-X and because of a poor train shunt and say, for example, three successive impulses of track circuit current of sufficient magnitude to operate the track relay CF get past the poor train shunt but the fourth impulse of current is insuflicient to operate relay CF, the above described operation is eiected up to and including the sixth operation step so that relays FSA, BSA, X2, Ci and C2 of the chain of relays are picked up. At the sev` enth operation step, however, relay FSA is re-' leased opening front contacts 32 and 34 because track relay CF is not picked up. The opening of front contact 32 deenergizes relay BSA to release that relay, and the opening of front contact 3 4 opens the stick circuits for relays X2, Cl and C2 and theserelays are released with the ren sult that all of the relays are reset at their released positions and the operation must be start'- ed all over again. Consequently, a proceed signal is not eiected unless the poor trainshunt persists for at least five impulses of the track circuit current.

It is apparent that the chain oi relays can includea'dditional counting relays controlled over circuits similar to those provided forrelays C! to C4, inclusive, and a number' greater 'than ve irnpulses is required before the proceed signal is displayed. Also the chain of relays can include less` than four counting relays if desired and a less number of track circuit impulses required before the proceed signal is effected.

Although my invention has been disclosed when used with a track circuit supplied with coded direct current, it is apparent it can be .used with a track circuit supplied with coded alternating current.

Although I have herein shown and described onlyone form of railway track circuit apparatus embodying -my invention, it is understood that various changes and modifications may be made therein within the scope of the appended claims without departing from the spirit and scope of my invention.

Having thus described my invention, what I claim is:

l. Trackcircuit apparatus for use with a track l circuit supplied with time spaced impulses of current for operating a code following track relay comprising, a first and a second control relay each provided with a slow release period suicient only to bridge from one impulse to the next of such track circuit current, means including a fronty contact of said code following track relay to energize said first control relay, means including a front contact of said first control relay and a back contact of said code following track relay to energize said second ocntrol relay, a preselected number of counting relays, circuit means including a front contactof each of said control relays and a back contact of said code following track relay to sequentially energize said counting relays in response to operation of the code following track relay, a stick circuit for each of said counting relays each of which stick circuits includes a front contact of each of said control relays to retain the counting relays picked up to count by the number of said counting relays picked up the successive current impulsesof the track circuit until all of the relays of said counting relays are picked up, and a signal circuit including a front contact of the last relay of said counting relays.

2. Track circuit apparatus for use with a track circuit supplied with time spaced impulses of current for operating a code following track relay comprising, a control relay having a slow release period sufiicient only to bridge from one impulse to the next of such track circuit current, means including a front contact of said code following track relay to energize said control relay, a first and a second repeater relay, means including a front contact of said control relay and a front contact of said code following track relay to alternately energize said first and second repeater relays in response to operation of the code following track relay, a preselected number of counting relays; a first circuit including a front contact of said control relay, a back contact of said code following track relay and a front contact of said first repeater relay to sequentially energize the odd numbered relays of said counting relays; a second circuit including a front contact of said control relay, a back contact of said code following track relay and a front contact of said second repeater relay to sequentially energize the even numbered relays of said counting relays; a stick circuit for each of said counting relays each of which stick circuits includes a front contact of said control relay to retain the counting relays picked up to count by the number of counting relays picked up the number of successive current impulses of the track circuit until all of said counting relays are picked up, and a signal circuit including a front contact of the last relay of said counting relays.

3. Track circuit apparatus for use with a track circuit supplied with time spaced impulses of current for operating a code following track relay comprising, a first and a second control relay each provided witha slow release period sufficient only to bridge from one impulse to the next of such track circuit current, means including a front contact of said code following track relay to energize said first control relay, means including a front contact of said first control relay and a back contact of said code following track relay to energize said second control relay, a preselected number of counting relays, circuit means including va front contact of each of said control relays and a back contact of said code following track relay to sequentially energize said counting relays in response to operation of the code following track relay, a stick circuit for each of said counting relays each of which stick circuits includes a front contact of each of said control relays to retain the counting relays picked up to count by the number of said counting relays picked up the successive current impulses of the track circuit until all of the relays of said counting relays are picked up, a rst signal circuit including either a back contact of the first,

control relayor in series a front contact of the first control relay and a back contact of the second control relay or in series a front contact of.

each of said control relays and a back contact of the last relay of said counting relays, and a second signal circuit including in series a front contact of each of said control relays and a front Contact of the last relay of said counting relays.

4. Track circuit apparatus for use with a track circuit supplied with time spaced impulses of current for operating a code following track relay comprising, a first and a second control relay each provided with a slow release period suii'icient only to bridge from one such track circuit current impulse to the next, means including a front contact of the code following track relay to energize said first control relay, means including a back contact of the code following track relay and a front contact of the first control relay to energize said second control relay, a first and a second repeater relay, circuit means including a front contact of each of said control relays and a front contact of said code following track relay to alternately energize said repeater relays in response to operation of the code following track relay, a preselected number of counting relays, a circuit including a back contact of said code following track relay and a front contact of said first repeater relay to energize the odd numbered relays of said counting relays one at a time, another circuit including a back contact of said code following track relay and a front contact of said second repeater relay to energize` the even numbered relays of said counting relays one at a time, a stick circuit for each of said counting relays each of which stick circuits includes a front contact of each of said control relays, and a signal circuit including a front contact of the last relay of said counting relays.

5. Track circuit apparatus for use with a track circuit supplied with time spaced impulses of current for operating a code following track relay comprising, a control relay having a slow release period sufcient only to bridge from one impulse to the next of such track circuit current, means` including a front contact of said code following track relay to energize said control relay, a rst and a second repeater relay, means including a front contact of said control relay and a front contact of said code following track relay to energize the rst repeater relay and release the second repeater relay in response to the even numbered impulses of the track circuit current and to energize the second repeater relay and release the rst repeater relay in response to the odd numbered impulses of the track circuit current after the first impulse, a preselected number of counting relays; a first circuit including a back contact of said code following track relay, a front contact of said first repeater relay and a back contact of said second repeater relay to energize the odd numbered relays of said counting relays one at a time; another circuit including a back contact of said code following track relay, a back contact of said first repeater relay and a front contact of said second repeater relay to energize the even numbered relays of said counting relays one at a time, a stick circuit for each of said counting relays each of which stick circuits includes a front contact of said control relay, and a signal circuit including a front contact of the last relay of said counting relays.

6. Track circuit apparatus for use with a track circuit supplied with time spaced impulses of current for operating a code following track relay comprising, a chain of relays including a control relay having a slow release period sufiicient to bridge the interval between successive impulses of such track circuit current only and a preselected number of counting relays, a pick-up circuit including a front contact of said code following track relay and a back contact of each of said counting relays to energize said control relay, a

stick circuit including a front contact of saidv code following track relay to retain said control relay picked up when the track relay is operated by each successive impulse of track circuit curcounting relays in response to operation of the track relay, a stick circuit for each of said count-v ing relays each of which stick circuits includes a front contact of said control relay to determine by the control relay picked up and number of counting relays picked up the number of successive impulses of track circuit current until all of the chain of relays are picked up, and a signal circuit including a front contact of said control relay and a front contact of the last relay of said counting relays.

'7. Track circuit apparatus for use with a track circuit supplied with time spaced impulses of current for operating a code following track relay comprising; a chain of relays consisting of a first land a second control relay each having a slow release period sufficient to bridge the interval between successive impulses of such track circuit current only, a first and a second repeater relay and a preselected number of counting relays; a pick-up circuit including a front contact of -said code following track relay and a back contact of each of the remaining relays of said chain of relays to energize said rst control relay, a stick circuit including a front contact of said code following track relay to retain said first control relay picked up, means including a front contact of said first control relay and a back contact of said code following track relay to energize said second control relay, means including a front contact of each of said control relays and a front contact of said code following track relay to alternately pick up and releasesaid first and second repeater relays, circuit means including a back contact of said code following track relayV and a contact of each of said repeater relays to sequentially energize said counting relays instep with operation of the track relay, a stick circuit for each of said counting relays each of which stick circuits includes a front contact of each of said control relays, and a signal circuit including a front contact of the last relay of said chain ofl relays.

ROBERT M. GILSON. 

